EP0605495B1 - Fatty-alcohol polyalkylene glycols with a narrow homologous-series distribution in low-foam dip-cleaning agents - Google Patents

Abstract

The invention concerns the use of fatty-alcohol polyalkylene glycol ethers with a narrow homologous-series distribution in alkaline dip-cleaning agents in addition to builder substances and/or builder mixtures.

Description

The invention relates to the use of fatty alcohol polyalkylene glycols with a narrow homolog distribution in low-foam immersion cleaners, in particular alkaline cleaners for industrial cleaning of metallic surfaces, based on concentrated aqueous solutions of alkaline builder substances and mixtures.

A large number of agents are used for the industrial cleaning of hard surfaces with aqueous solutions. The most important components of these substances are builder and surfactant systems alone and in combination with each other. The properties of these base mixtures of builders and surfactants often have to be adapted to the respective application for practical use by adding further ingredients, such as complexing agents and corrosion inhibitors.

The aqueous, mildly alkaline solutions of the immersion cleaners usually have a pH of about 10 to 11.5. They are used in particular for difficult cleaning tasks, for example for removing thick oil and pigment soiling in repair shops and for cleaning containers and systems. These alkaline immersion cleaners can also be used for fine cleaning of metallic surfaces, provided that clean metallic surfaces are required. This applies, for example, to cleaning before and after hardening processes, cleaning strip steel before annealing and coating, and pretreatment of workpieces in electroplating, phosphating, painting shops and Enamelling companies. With the aqueous solutions of the alkaline immersion cleaners, a very high level of purity of the workpiece surfaces and, at the same time, good dirt discharge capacity of the bath are expected. In addition to manual cleaning, processes such as dipping, brushing, spraying, ultrasound and electrolysis alone or in combination with one another are of greater or lesser importance. Typical alkaline immersion cleaners are produced as a powder by mixing 80 to 100% alkaline builder substance and 0 to 20% of various anionic and / or nonionic surfactants. The most common inorganic builders are alkaline hydroxides, silicates, phosphates and carbonates of sodium and / or potassium. Depending on requirements, gluconates, polyalkanolamines, polycarboxylic acids, polyoxycarboxylic acids and phosphonates are also used as complexing agents. The surfactant mixtures usually consist of low and highly ethoxylated or propoxylated alkylphenols and / or fatty alcohols with different chain lengths. Nonylphenol alkoxylates are characterized by excellent technical properties and are universally applicable surfactants for a variety of detergents and cleaning agents, as well as emulsifiers for a variety of technical applications. The degreasing properties of nonylphenol alkoxylates are particularly pronounced on both metallic surfaces and textile fabrics. However, the ecological assessment is disadvantageous for this product group. It has been shown that alkylphenol ethoxylates form toxic metabolites during biodegradation.

GB-A-1 445 716 relates to detergent formulations, in particular for cleaning metallic surfaces, containing a mixture of certain nonionic surfactants of the linear alcohol ethoxylate type, optionally together with other customary detergent components such as inorganic builders. This mixture is distinguished by the fact that it contains at least two such surfactants which have a chain length in the fatty alcohol residue of 8 to 13 carbon atoms and a degree of ethoxylation (EO%) of 55 to 85%, but they differ in the degree of ethoxylation. With these surfactants, the chain length of the fatty alcohol and the degree of ethoxylation are coordinated with one another such that the first surfactant has an EO content of less than 70% and the second surfactant has an EO content of more than 65%, the difference between these EO contents is at least 10. The proportion by weight of the surfactant with the lower EO content is in the range from 10 to 100% based on that of the surfactant with the higher EO content. Such formulations have an improved cleaning effect.

US-A-4 048 121 describes metal cleaner formulations containing alkaline builders, sodium gluconate, sodium ethylenediaminetetraacetate, kerosene and a biodegradable wetting agent mixture consisting of three components. Two of these components are linear, primary alcohol polyethers, the first component having a cloud point of approximately 40 ° C. and the second component having a cloud point of approximately 26 ° C. The third component consists of a linear alcohol alkoxylate with a cloud point of approx. 20 ° C.

US-A-3 888 783 describes cleaner formulations for tinned metal surfaces. The aqueous cleaners contain metasilicates, condensed phosphates, sodium borate and optionally surfactants. Suitable surfactants are, for example, ethoxylated straight-chain alcohols or octyl- or nonylphenoxy-polyethoxyethanols.

The presentation of SU-A-372 250 in database WPI / DERWENT 73-68366 U relates to cleaners for metal surfaces to remove resinous deposits. The cleaners contain oxyethylated fatty alcohols, alkylbenzylpyridinium chloride, pine oil extract, sodium metasilicate, sodium triphosphate and calcined soda.

The addition products of ethylene and / or propylene oxide with primary alcohols, so-called fatty alcohol polyalkylene glycol ethers, are of great importance as nonionic surfactants due to their excellent detergent properties and their high solubility in cold water for the production of washing, rinsing and Detergents. However, in the course of the alkoxylation, which is generally carried out in the presence of readily soluble alkali metal hydroxides or alcoholates, there is no selective addition of a discrete number of ethylene and / or propylene oxide units to one molecule of the alcohol; the reaction follows more or less statistical laws and leads to a mixture of homologous addition products whose degrees of alkoxylation encompass a broad spectrum.

From J. Am. Oil Chem. Soc. 63 , 691 (1986) and HAPPI (Household & Personal Products Industry), 23 , (1986), 32, it is known that the distribution of the degrees of alkoxylation in the mixture of alcohol alkoxylates, the so-called "homolog distribution", the properties of the addition products obtained significantly influenced.

Suitable processes for the production of fatty alcohol polyalkylene glycol ethers with a narrow homolog distribution are known, for example, from DE-A-38 43 713 and US-A-4 962 237. In both cases, the alkoxylation of fatty alcohols is carried out in the presence of inorganic layer compounds, for example calcined hydrotalcite.

The object of the present invention was to find substitution products for alkylphenol alkoxylates which have at least comparable application properties and which, according to the current state of knowledge, are also ecologically harmless.

• (a) 85 bis 98 Gew.-% eines Builderstoffes oder eines Buildergemisches und
• (b) 2 bis 15 Gew.-% Fettalkoholpolyalkylenglykolether mit eingeengter Homologenverteilung, enthaltend einen aliphatischen Kohlenwasserstoffrest mit 6 bis 24 C-Atomen und 0, 1, 2 oder 3 olefinischen Doppelbindungen mit durchschnittlich 1 bis 30 Mol Ethylen- und/oder Propylenoxid pro Mol Fettalkohol, gewonnen durch Alkoxylierung der entsprechenden Fettalkohole in Gegenwart von anorganischen Schichtverbindungen vom Typ calcinierter natürlicher oder synthetischer Hydrotalcite.

The solution to the above problem therefore consists in alkaline immersion cleaners based on alkaline builders and surfactants, characterized in that they contain:

• (a) 85 to 98% by weight of a builder substance or a builder mixture and
• (b) 2 to 15 wt .-% fatty alcohol polyalkylene glycol ether with a narrow homolog distribution, containing an aliphatic hydrocarbon radical with 6 to 24 carbon atoms and 0, 1, 2 or 3 olefinic double bonds with an average of 1 to 30 moles of ethylene and / or propylene oxide per mole Fatty alcohol obtained by alkoxylation of the corresponding fatty alcohols in the presence of inorganic layered compounds of the calcined natural or synthetic hydrotalcite type.

It has surprisingly been found that alkaline immersion cleaners according to the invention have greatly improved application properties compared to comparable cleaners based on alkylphenol alkoxylates. Corresponding advantages in terms of application technology have also been achieved in comparison with nonionic fatty alcohol polyalkylene glycol ethers which have been customary in the prior art and have a standard (read: broad) homolog distribution.

The dip cleaners according to the invention preferably contain at least one alkali metal silicate and / or one alkali metal phosphate as a builder.

The usual industrial industrial cleaners are usually divided into silicate and phosphate cleaners. Here, the powdered silicate cleaners based on sodium metasilicate and caustic soda are generally characterized by the SiO₂ / Na₂O weight or molar ratio that occurs when the products are dissolved in water and generally in the range of SiO₂ / Na₂O = ( 0.1 to 2.2): 1 lies. Such cleaners can be dissolved at room temperature up to a maximum concentration of approx. 100 g / l if the corresponding sodium salts and caustic soda are used. However, if the corresponding potassium salts and potassium hydroxide are used, solutions with a maximum concentration of 500 g / l result.

According to a preferred embodiment of the present invention, the alkaline immersion cleaners are characterized in that the In addition to an alkali metal silicate and / or an alkali metal phosphate, builder mixtures also contain alkali metal hydroxides and / or alkali metal carbonates and / or alkali metal gluconates and / or alkanolamines.

The alkaline immersion cleaners according to the invention can thus contain the following builder substances: either alkali metal silicate and alkali metal phosphate, in each case alone or in a mixture. In addition, there is the preferred possibility within the meaning of the invention of combining these builder substances with alkali metal hydroxides, alkali metal carbonates, alkali metal gluconates and alkanolamines, it being possible for such combinations to contain one or more of the additional builder substances.

For the purposes of the invention, sodium and / or potassium are preferably used as alkali metals. Mixtures of corresponding sodium and potassium compounds are preferably used, the proportion of potassium ions exceeding that of sodium ions.

If we are talking about alkali metal silicates, then according to the invention this means alkali metal silicates with a molar ratio SiO₂ / Me₂O in the range from (1 to 3.5): 1 (Me = Na and / or K). Powdered sodium silicates with the above-mentioned SiO₂ / Na₂O molar ratio are preferably used in the sense of the invention, in particular sodium metasilicate, molar ratio SiO₂ / Na₂O = 1: 1, either anhydrous or in the form of the pentahydrate or nonahydrate, or readily soluble, powdered sodium silicate with a molar ratio of SiO₂ / Na₂O = (2.0 to 2.1): 1 (commercial product PORTIL ^(R) AW, from Henkel KGaA).

In the context of the invention, the term alkali metal phosphates is understood to mean alkali metal orthophosphates, pyrophosphates and triphosphates (also called tripolyphosphates). Of these, however, the triphosphates are preferred according to the invention, in particular the potassium triphosphate.

If such phosphates are used in combination with the silicates discussed above, the proportion of silicate in the aqueous builder solutions should generally predominate; i.e. the phosphate content is in the range from about 0.1 to 10% by weight, based on the aqueous builder solution.

The alkanolamines mentioned are preferably 1 to 3 times amines substituted by hydroxylalkyl groups - having 1 to 4 carbon atoms in the alkyl radical. Di- and / or triethanolamines are preferably used for the purposes of the invention.

Suitable starting materials for the fatty alcohol polyalkylene glycol ethers are fatty alcohols with 6 to 24 carbon atoms in the fatty alcohol residue and 0, 1, 2 or 3 double bonds. Typical examples of this are capronic alcohol, caprylic alcohol, capric alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, gadoleyl alcohol, behenyl alcohol or erucyl alcohol. Saturated fatty alcohols with 8 to 18 carbon atoms in the fatty alcohol radical, in particular lauryl alcohol, are preferably used.

As is customary in fat chemistry, these alcohols can also be in the form of technical mixtures, such as are obtainable, for example, by high-pressure hydrogenation of fatty acid methyl ester cuts of plant or animal origin or by hydrogenation of technical aldehyde fractions from Roelen's oxosynthesis. Prefers technical coconut alcohol, a mixture of fatty alcohols with 12 to 18 carbon atoms in the fatty alcohol residue, is used.

The fatty alcohol polyalkylene glycol ethers are produced in the presence of layered compounds with ethylene and / or propylene oxide.

In the context of the present invention, layered compounds are to be understood as natural or synthetic, optionally chemically modified hydrotalcites. In the course of the reaction, the layer compounds insoluble in the reaction mixture are colloidally dispersed, which generally means that the removal of the catalyst required after the alkoxylation is associated with considerable difficulties, for example clogging of the filter pores, frequent filter changes, etc. According to the present invention, however, it is generally not necessary to separate these catalysts, since the presence of the layered compounds in the immersion cleaners according to the invention does not constitute a disadvantage. This represents an essential cost factor in the manufacture of the immersion cleaners according to the invention.

The fatty alcohol polyalkylene glycol ethers to be used for the purposes of the present invention contain an aliphatic hydrocarbon radical (fatty alcohol radical) having 6 to 24 carbon atoms and 0, 1, 2 or 3 olefinic double bonds with an average of 1 to 30 moles of ethylene and / or propylene oxide per mole of fatty alcohol. In particular, those fatty alcohol polyalkylene glycol ethers are preferred according to the invention which contain an aliphatic hydrocarbon residue (fatty alcohol residue) with 8 to 18 carbon atoms and with an average of 6 to 20 moles of ethylene and / or propylene oxide per mole of fatty alcohol.

If we are talking about fatty alcohol polyalkylene glycol ethers with a defined average amount of ethylene and / or propylene oxide per mole of fatty alcohol, this means a narrow homolog distribution, which is characterized in that the proportions of low alkoxylated fatty alcohol are, for example, 1, 2 or 3 moles Alkylene oxide per mole is also present in reduced form, as are highly alkoxylated products with 14 to 20 moles of alkylene oxide per mole of fatty alcohol, for example if a fatty alcohol with 7 moles of ethylene oxide per mole is mentioned. In the case of fatty alcohol polyalkylene glycol ethers with a standard homolog distribution, the technical products generally contain a more or less large proportion of low alkoxylated product as well as products with a very high degree of alkoxylation. In addition, considerable amounts of alkylene oxide-free fatty alcohol are contained here, which as such show practically no surface-relaxing effect.

Accordingly, it is also possible according to the present invention to use mixtures of two or more fatty alcohol polyalkylene glycol ethers which differ from fatty alcohol polyalkylene glycol ethers with a standard homolog distribution in that degrees of alkoxylation in the range from 0 to 3 and above 20 moles of alkylene glycol per mole of fatty alcohol are virtually non-existent occur when you start from a fatty alcohol polyalkylene glycol with a narrow homolog distribution and a degree of alkoxylation of 10 and 12 moles of alkylene glycol per mole of fatty alcohol.

The present invention furthermore relates to the use of the immersion cleaners according to the invention in the cleaning of metal surfaces, in particular steel, non-ferrous metals, copper and zinc, before finishing processes such as phosphating, galvanizing, Enamelling and painting as well as intermediate cleaning before processing, especially before the annealing.

Although the dip cleaners according to the invention can of course also be used in undiluted form, it is preferred for the purposes of the present invention to use the dip cleaners in such a way that an aqueous solution containing 1 to 20% by weight of dip cleaner is used for the cleaning process mentioned above. Accordingly, preferably used solutions of the immersion cleaners contain 10 to 200 g / l of the cleaner concentrates according to the invention.

The advantage of the liquid, alkaline immersion cleaners according to the invention is, on the one hand, that they have a high active ingredient content in builders and at the same time contain surfactants in high concentration.

The combination of builder substances and fatty alcohol polyalkylene glycol ethers according to the invention within the immersion cleaners means that suitable products can be offered for all applications in industrial technical cleaning. Cleaners can be formulated for spraying, brushing, dipping and ultrasonic processes as well as for electrolytic cleaning. Using suitable combinations, predetermined cloud points can be set and high-temperature or low-temperature immersion cleaners can be prepared.

In addition to the active ingredient components mentioned above, immersion cleaners according to the invention can of course also contain further constituents which are commonly used in alkaline cleaning agents, such as, for example, defoamers, corrosion inhibitors, complexing agents and / or the like. Examples of compounds which are particularly suitable in the context of the invention are:

Defoamer:

C _{12/18 fatty} alcohol (coconut alcohol) polyethylene glycol butyl ether, adducts of ethylene oxide and propylene oxide with fatty alcohols, as are sold, for example, by BASF AG, Ludwigshafen, under the name PLURAFAC ^(R) , each in amounts of 0.1 up to 5% by weight, based on the alkaline immersion cleaner.

Corrosion inhibitors:

(for non-ferrous metals) benzotriazole, tolyltriazole; each in amounts of 0.1 to 5 wt .-%, based on the immersion cleaner.

Complexing agent:

Polycarboxylic acids, e.g. Polyacrylates; Phosphonic acids, such as hydroxyethane-1,1-diphosphonic acid (HEDP), amino-tris (methylenephosphonic acid) (ATMP), or their water-soluble salts; Aminopolycarboxylic acids, e.g. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) or their water-soluble salts; Polyoxycarboxylic acids, e.g. Citric acid or its salts; each in amounts of 0.1 to 10 wt .-%, based on the immersion cleaner.

The addition of such compounds is generally not required in the context of the present invention; Such additives can rather be advantageous, depending on the application, the quantities required in each case being matched to the need.

The immersion cleaners according to the invention are generally prepared in the following manner: the aqueous builder solutions are first mixed with one another with stirring and at room temperature, for example a water glass solution with potassium hydroxide solution and, if appropriate, potassium triphosphate solution. The remaining constituents, ie the surfactants and optionally additives, are then likewise added to the concentrated aqueous builder solution with stirring. To prepare dilute application solutions, ie cleaning solutions, the immersion cleaners are generally metered directly into the cleaning bath with stirring.

The examples given below serve to illustrate the invention, but without restricting it to the builders and surfactants specifically mentioned here.

Examples General working instructions

Alkaline immersion cleaners, containing an aqueous solution of 36.8 g / l builder and 3.2 g / l surfactant each, were prepared by stirring the surfactant into the aqueous builder solution. In Examples 1 to 3 below and Comparative Examples 1 and 2, the builder each consisted of 3.7 g / l sodium pyrophosphate, 5.9 g / l sodium metasilicate and 9.9 g / l sodium carbonate. The surfactant base can be found in each of the examples and comparative examples.

example 1

In addition to the builder mentioned above, the immersion cleaner contained a 1: 1 mixture of a fatty alcohol ethoxylate with 12 to 18 carbon atoms in the fatty alcohol residue and an average degree of ethoxylation of 8 moles of fatty alcohol with a narrow homolog distribution and another fatty alcohol ethoxylate with 12 to 18 carbon atoms in the fatty alcohol residue and one average degree of ethoxylation of 16 moles per mole of fatty alcohol with a narrow homolog distribution. Tables 1 and 2 show the properties of such an immersion cleaner.

Example 2

Instead of the combination of surfactants mentioned in Example 1, a 1: 1 mixture of a fatty alcohol ethoxylate with 12 to 18 carbon atoms in the fatty alcohol residue and an average degree of ethoxylation of 6 moles per mole of fatty alcohol with a narrow homolog distribution and a further fatty alcohol ethoxylate with 12 to 18 carbon atoms was used in the fatty alcohol residue and an average degree of ethoxylation of 20 mol per Mol of fatty alcohol with a narrow homolog distribution. Tables 1 and 2 also show the properties of this immersion cleaner.

Example 3

Instead of the surfactant combination of Example 1, a fatty alcohol ethoxylate with 12 to 18 carbon atoms and an average degree of ethoxylation of 12 moles per mole of fatty alcohol with a narrow homolog distribution was used.

Tables 1 and 2 below show the data obtained from this immersion cleaner.

Comparative Example 1

Instead of the surfactant combination of Example 1, a 1: 1 mixture of a fatty alcohol ethoxylate with 12 to 18 C atoms and an average degree of ethoxylation of 9.5 per mole of fatty alcohol with standard homolog distribution and an alkylbenzenesulfonate with 10 to 13 C atoms in the alkyl radical was used. Tables 1 and 2 below also give the data obtained here.

Comparative Example 2

Instead of the surfactant combination of Example 1, a fatty alcohol polyalkylene glycol ether of a fatty alcohol ethoxylate with 10 to 18 carbon atoms and an average degree of ethoxylation of 10 moles per mole of fatty alcohol with standard homolog distribution was used. Tables 1 and 2 also show the data here. Table 1 example Primary foam (ml) Half-life (min) Cloud point (° C) 1 450 1.75 69 2nd 400 2.00 63 3rd 400 1.50 75 See 1 710 4.50 more than 100 See 2 550 2.0 more than 100 example Water wettability Carbon values Oil loading capacity (g / l) a) b) c) d) e) 1 + 9 10th - 3rd 5 20-23 2nd + 9 8th 5 3rd 7 14-17 3rd + - 9 4th - 5 17-20 See 1 + 10th 11 - 6 17th 8-11

The foam test for determining the primary foam was carried out at 60 ° C. according to DIN 53902, part 1. The primary foam and foam disintegration over 10 min were observed. To determine the cloud point, the solutions were slowly heated while observing the temperature. The cloud point of the surfactant mixtures should be above 60 ° C.

To determine the cleaning effect, the immersion cleaners were greased with a corrosion protection oil "WD 40" in each case at 60 ° C and annealed at 75 ° C for 24 h.

Test sheets made of ST 1203 were immersed at 60 ° C for 5 minutes and then the water wettability was assessed optically and a combustion analysis was carried out at 400/600 ° C. The data obtained are shown in column a) of Table 2. Column b) shows the corresponding data obtained when the corrosion protection oil "WD 40" was replaced by a cutting oil "KS 212" from Shell Makron GmbH.

Column c) of Table 2 shows the data obtained when the sheets of ST 1203 were replaced by CuZn 37 sheets. While column d) shows the data when greased with the corrosion protection oil "WD 40", column e) contains the data when greased with the cutting oil "KS 212". Column e) shows the data obtained when the CuZn 37 sheets were immersed in immersion cleaning solutions after they had been greased with a cooling lubricant (P3-Multan ^R 86-7) containing non-ferrous metals.

The immersion cleaners were loaded with the corrosion protection oil "WD 40" to check the maximum oil load. Test plates were then immersed for 5 minutes and the water wettability after the sink was assessed optically.

Claims (7)

1. Alkaline dip cleaners based on alkaline builders and surfactants, characterized in that they contain:

   (a) 85 to 98% by weight of a builder or builder mixture and

   (b) 2 to 15% by weight of narrow-range fatty alcohol polyalkylene glycol ethers which contain an aliphatic hydrocarbon radical with 6 to 24 carbon atoms and 0, 1, 2 or 3 olefinic double bonds and an average of 1 to 30 moles of ethylene and/or propylene oxide per mole of fatty alcohol and which are obtained by alkoxylation of the corresponding fatty alcohols in the presence of inorganic layer compounds of the calcined natural or synthetic hydrotalcite type.
2. Dip cleaners as claimed in claim 1, characterized in that they contain at least one alkali metal silicate and/or alkali metal phosphate as builder(s).
3. Dip cleaners as claimed in claim 1 and/or 2, characterized in that, in addition to alkali metal silicate and/or alkali metal phosphate, they also contain alkali metal hydroxides and/or alkali metal carbonates and/or alkali metal gluconates and/or alkanolamines.
4. Dip cleaners as claimed in one or more of claims 1 to 3, characterized in that the alkali metal is sodium and/or potassium.
5. Dip cleaners as claimed in one or more of claims 1 to 4, characterized in that the fatty alcohol polyalkylene glycol ethers contain an aliphatic hydrocarbon radical with 8 to 18 carbon atoms and an average of 6 to 20 moles of ethylene and/or propylene oxide per mole of fatty alcohol.
6. Dip cleaners as claimed in one or more of claims 1 to 5 containing mixtures of two or more narrow-range fatty alcohol polyalkylene glycol ethers.
7. The use of the dip cleaners claimed in one or more of claims 1 to 6 for cleaning metal surfaces, particularly steel, nonferrous metals, copper and zinc, before finishing processes, such as phosphating, electroplating, enamelling and painting, and for intermediate cleaning before processing, more particularly before annealing.